This invention relates to improved actuators for automatically operating a valve or other controlled element in response to an earthquake or other shock forces of predetermined intensity.
Various types of devices have been proposed in the past for automatically closing a valve or achieving another desired purpose in the event of an earthquake, usually with the intention of preventing or minimizing damage resultant from the quake. The most common intended use for such devices is to close off the flow of gas through a pipeline in order to prevent the development or spread of fire. The devices utilize as a shock sensitive element an inertia actuated weight mounted in a housing or in association with another structure in a relation such that relative displacement between the weight and that structure automatically actuates the controlled element when seismic or other shock forces are encountered.